Fieldrate

Just as Progressive video has a Framerate that specifies how many frames are displayed per second, interlaced video has a fieldrate that determines how many fields display in a second. Standard fieldrates are 50 or 59.94 fields per second for analog video, and 50, 59.94, or 60 fields per second for digital signals.

For Frame based video the fieldrate can be calculated by doubling the framerate. For example, in an interlaced MPEG-2 file encoded at 29.97fps (frames per second), the fieldrate would be 59.94 fields per second.